This invention relates to an automatic weighing system and more particularly to an automatic weighing system of a combinational weighing type. It further relates to a device for feeding articles to such a system in a reliable manner and an energy- and space-saving hopper-driving means.
There are many kinds of particle-like products such as peanuts and block-type products such as green peppers which are being sold in stores and supermarkets. When they are displayed for sale, it is frequently required to package them in units of a predetermined weight. In such a situation, it is necessary not only to make absolutely certain that each package should contain at least the predetermined weight but also to minimize the excess weight of each package over this predetermined level. Since any process involving manual weighing is out of the question, automatic weighing and packaging systems of many types have come to be popularly used.
U.S. Pat. No. 4,398,612 issued Aug. 16, 1983 and assigned to the present assignee discloses an automatic weighing system of a combinational weighing type having a number of article batch handling units arrayed radially. Articles to be weighed are typically transported by a conveyor and dropped onto an article feeding system which distributes them into the individual article batch handling units. Weight-measuring means associated with the individual article batch handling units are electrically connected to a computer which computes combinations of weight values obtained from these weight-measuring means and selects a combination according to a predetermined criterion such as the combination which gives a total weight that is within a preselected range.
The invention as disclosed in U.S. Pat. No. 4,398,612 such as Models CCW-201RLC and CCW-211RLC manufactured and sold by the assignee corporation has revealed the desirability of certain improvements. The apparatus utilized according to the aforementioned patent as well as the aforementioned models for controlling the rate at which the articles to be weighed are supplied to the article batch handling units comprises a light-emitting element and a light-receiving element forming together a photoelectric sensor system. The article feeding system includes a dispersion table and a decision whether or not to bring in more articles to be weighed is made by determining with the aforementioned sensor system whether the pile of the articles to be weighed as accumulated on the dispersion table is high enough to block the beam from the light-emitting element.
The method of controlling the rate of supply as outlined above could be made still more accurate if the weight, rather than the height, of the articles on the dispersion table is depended upon in deciding whether or not to drive the conveyor to bring additional articles to the article feeding system. In other words, since the intermittent discharging of the articles at the bottom is controlled to be at a predetermined rate measured in weight, the system can be operated more dependably if the supply of the same articles from above is also controlled by weight. It is because the height of a pile is not an accurate measure of its weight especially where, as here, the articles constituting the pile are vibrating so that the shape of the pile is likely to keep changing, and there is not simple relationship to be expected between the actual rate of supply and that of discharge.